1. Field of the Invention
The present invention relates to a milk whey protein-containing powder obtained by reacting a solution containing a milk whey protein with transglutaminase, heating the reaction solution at a high temperature, then drying the resulting product. The invention also relates to an animal meat paste food, a fish meat paste food and emulsified foods obtained by using the milk-whey protein-containing powder.
2. Discussion of the Background
Milk whey protein is found in whey, a by-product from the production of cheese or casein from milk or a skim milk powder. In countries where cheese and so forth are produced, attempts have been made to recover milk whey protein and use it as a food material with the aim of environmental conservation and to more effectively use natural resources.
The production of milk whey protein concentrate via ultrafiltration has been reported in which the protein content of the concentrate is between approximately 50 and 70%. Further, a separate whey protein having a protein content of approximately 90% or more has been produced to improve the gelation, emulsifying capacity and foaming capacity of the protein.
Meanwhile, in recent years, studies on milk whey protein-containing products having lower protein content (approximately 30%) than that of conventional products as a food material have been actively conducted at a global level in order to effectively utilize the active ingredients of whey, such as protein, sugar, mineral and the like in the diet with a minimum of whey processing.
When the milk whey protein-containing product discharged as a by-product is used in various foods, the foods have a rough feel as well as a bad taste upon passage through the throat owing to the milk whey protein, and is therefore undesirable. The rough feeling and the bad taste upon passage through the throat do not apply to the overall milk protein. This is because these problems do not apply to caseins that are a main component of a milk protein.
To solve the problems of the rough feeling and the bad feeling upon passage through the throat which are found in the milk whey protein, a technique to lower the molecular weight of this protein using an enzyme has been generally employed. However, when the molecular weight of a protein using an enzyme, the desired gelation properties of the milk whey protein are decreased.
Accordingly, a milk whey protein-containing powder (1) which retains the desirable characteristic properties of milk whey protein, such as gelation, emulsifying capacity and the like and (2) which is excellent in throat feel and taste upon eating has been in demand. To cope with such problems, the following attempts have been already made.
The retention of gelatinization ability and the decrease in number of bacteria have been attempted by bringing a non-denatured whey protein powder in contact with superheated steam of 110 to 130.degree. C. for 10 to 20 seconds (refer to Japanese Patent Publication No. 108, 191/1995). This method is effective for retaining the gelatinization ability and decreasing the number of bacteria. However, the problems such as the rough feeling and the bad taste upon passage through the throat which are caused by the heating even for a short period of time still remain.
A technique has also been studied in which protein particles having an average particle diameter of from approximately 40 to 50 .mu.m are prepared by partially denaturing a milk whey protein (degree of denaturation between 55 and 80%), and added to foods such as mayonnaise, salad sauce, ice cream and the like (U.S. Pat. No. 5,494,696). However, the above-described problems relating to the rough feeling and the bad taste upon passage through the throat have not completely been eliminated.
Accordingly, the above-mentioned problem of providing a milk whey protein-containing powder that both (1) retains the desirable characteristic properties of milk whey protein, such as gelation, emulsifying capacity, and the like, and (2) is excellent in throat feel and taste has not yet been realized.
Other researchers, Shin-Ya Tanimoto and John E. Kinsel (J. Agric. Food Chem., 1988, 36, 281-285) have reported the thermal stability of a polymer mixture obtained by treating .beta.-lactoglobulin with transglutaminase at 99.degree. C. or less and the effect on protein solubility. Their experiments revealed that the insolubilization of a protein is inhibited. However, the properties of the thus-treated protein, for example, gelation, water holding capacity, emulsifying and foaming capacity, were not examined at all. Moreover, feeling upon eating, such as a feeling upon passage through the throat or the like, has not been referred to at all. Further, this report has described experimental results in a pure system of .beta.-lactoglobulin which is a only minor component of milk protein. However, there is nothing in this report to suggest the treatment of the overall milk whey protein-containing product that contains various substances other than B-lactoglobulin.
In a modified milk protein-containing material (Japanese Laid-Open (Kokai) No. 160,957/1991) and a pickle for processed edible meat (Japanese Laid-Open (Kokai) No. 255,426/1995), a milk protein is reacted with a transglutaminase. Casein, a major component of a milk protein, is imagined as this milk protein. However, these documents do not suggest the elimination of the problems of the milk whey protein solved by the present invention, such as the rough throat feel that nevertheless do not apply to casein.